This invention relates to blood sampling devices, and it is particularly concerned with devices suitable for use on large animals, such as cattle, with thick hides.
To take a sample, first it is necessary to draw blood from as small an incision as possible, and then to collect the drop or drops that then appear as quickly as possible, avoiding contamination. While the sample will then have to be conveyed from farm to laboratory, the actual pricking implement should be made safe and disposable.
It is the aim of this invention to provide a device where these features are combined.
According to the present invention there is provided a blood sampling deice comprising a hollow barrel housing a pricker urged toward a retracted position from a forward end of the barrel by spring means, and a container that co-operates with the rear end of the barrel, the container forming an operating member which is pressed in the forward direction to project the pricker from the barrel, being adapted to collect and contain the blood sample derived from the pricker, and being separable from the barrel to convey the sample elsewhere, the barrel with the pricker retracted by the spring means being disposable.
Preferably, the barrel is integrally moulded in plastics material in two halves mutually hinged about a longitudinal axis, the halves then being closed around the spring means and pricker to provide guide means for the pricker.
Conveniently the container when serving as the operating member, acts on an element connected to the pricker by a shearable bridge, this bridge breaking as pressure greater than that which ensures full penetration of the pricker is applied. The user can sense the breakage by the container shooting forward in relation to the barrel, and in completing its travel it gives a final push to the barrel.
The barrel, on closure, can be structured to form two diametrically opposed longitudinal slots in which are received wings of said element, allowing longitudinal but not rotational movement thereof. Preferably, the tip of the pricker on manufacture is embedded in a twist-off cap integrally moulded with the body of the pricker, the cap initially being external of the forward end of the barrel and keeping the pricker in a forward position with the spring means energised. The restraint on rotation allows the twist-off action to be carried out easily, and it is only then that the pricker can retract ready for use.
Preferably, the container is guided by the barrel and has a hollow compartment with a closed forward end projecting into the barrel to act on said pricker. It therefore acts like a piston rod. The compartment will contain an absorbent filling accessible through its rear end to soak up the blood sample when the pricker has been withdrawn and the device reversed. The container will have a closure cap for the rear end of the compartment, and as soon as a sample is taken, the cap is closed over and the container removed from the barrel.
The container conveniently has a snap engagement with the barrel.